Galaga Repair


When the testing device / software application loads the test table for Galaga, the hardware interface device switches to the Z-80 type microprocessor, and the various sections of circuitry which make up the Galaga game PCB can be examined and verified.
The 3 independent Z80 microprocessors which exist on a Galaga board are each tested individually, providing the ability to prove reliable operation of each computer section. All functions can be verified to work from any one of the three processor sockets, thereby proving/disproving circuit operation throughout. Every Galaga PCB repair will under go the following test procedure, as outlined here: Galaga Test Procedure.
Each microprocessor socket on the Galaga CPU is recorded, and the program ranges are compared with master data reference files. All program variations are supported. Galaga Program Example If any of these program chips fail to match with the reference file, the problem is corrected by reprogramming or replacement. If while testing Z-80 socket 3J the program chip is found to be the regular fire version, an optional rapid fire upgrade is available.

Additionally, each Z-80 socket is tested for its ability to communicate with all memory chips located on the video board. For an example, click here:
Sequence of events testing RAM

Each position is tested for proper address decoding, data transfer, and read - write operations. All buffers and transceiver chips are tested with several test sequence groups, which are designed to precisely identify failures to the component level. Interrupt and control is then tested.
Galaga CPU 74LS259 location 3C

Star speed, star direction and screen flip for player 2 are all tested on the Galaga board by using a software module which is specifically designed to troubleshoot the 74LS259 chip at location 5K on the video board, which controls this part of the circuit. An example of this testing phase in process: Adjust star operation and screen invert on Galaga.

Video tests, background and foreground color tests, text screen, and moving character tests are all performed on the board being serviced: Load test patterns to Galaga video Ram

All boards are tested for correct dip switch operation in real time. Tests are run for continuous as well as intermittent contact conditions: Examine Galaga Dip Switches

Control panel inputs, (player 1 and 2) are all verified. The sound and music sections of the circuit are also tested. An example for testing the 7489 memory chips for music and sounds on a Galaga Cpu is essentially the same circuit as Ms Pacman viewable here:
Verifying and exploring the music circuitry.

Methods used to test / verify / troubleshoot different areas of the circuit include the ability to control specific chip operation.
This is done by selecting the correct control module, which is designed for that particular area of the circuit.
Adjustment of the sliders, or pointing and clicking the desired pin on the IC will cause the desired result, such as in this example of testing the reset circuit:

Galaga CPU Buffered Address Decode

   Sometimes failure does not occur until this process is performed. During this testing phase, slight shock and vibration is introduced to the Galaga PCB set, and re-testing is performed. If this test fails, the activity is recorded. Intermittent connections are captured, explored, and then analyzed.
      Faults are highlighted while viewing the "Error Analysis" screen, and the possible causes are listed by probability.

Error Analysis utilizing the GLS1 Electronics
Computer Aided Testing System

Boards are burned in for a minimum of 72 hours. Note that if your board does not pass burn-in, (and about 25% of boards received do not pass burn-in), they will start this burn-in process over. I find that 72+ consecutive hours of error-free operation increases the reliability of these boards, and I feel confident the board will function well beyond the 90-day warranty I provide.
Boards submitted for repair must be complete, (all custom IC's) and in repairable condition, (not physically damaged).
The price for this repair service is US $125.00.

If your Galaga PCB is missing parts, it can still be repaired, send in PCB for estimate, or contact GLS1 Electronics beforehand.

This information on this page was last updated on May 26th, 2008.

      Payment by check is acceptable, please enclose check inside box with Galaga game PCB when shipping. When paying by check, please include return shipping of $12.00.
      All return shipping from this shop is done USPS priority mail, which usually means a 2-day delivery time.
     GLS1 Electronics will also consider non-working Galaga PCB trade-ins as payment for repair services.

Contact me at: gls1@gls1electronics.com for more information regarding Galaga repair.

	System Description
	Galaga Test Procedure
	Galaga Test Examples
	Galaga Test Table
	Galaga Power Supply

	Index of Links
	Asteroids or Ms Pacman PCB's also tested and repaired using computer.

Galaga PCB Repair
for your Galaga video game
Computer Aided Testing System


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